With the splash shields out, run the harness so one female plug comes through the hole in the back of each headlight cup where the old plugs came through. The female plugs at each end of the new harness (with three wires each) are for the low-beam lights, and the other female plugs (with two wires each) are for the high-beam lights. The wiring harness is the secret to making the system work and negates rewiring the car. When the new harness is installed, it relegates the old one to only having to deal with low currents passing through the old wiring and headlight switch. The current now going through the old wiring only controls the relays which, along with the new wiring, now handle the current of the high-powered headlights. The three no-longer-used headlight plugs can be tucked away behind the headlight buckets.